The primary objective of the Mouse Genetics Core is to prepare various mutations in neuronal nicotinic acetylcholine receptors (neuronal nAChRs) and to provide these mice to the three projects and to the Morphology Core. The rationale for the overall strategy is based on the belief that genetic manipulation in the mouse is one of the most powerful methods available for delineating the function of genes and that this will be a valuable approach for understanding the role of nAChRs in nicotine addiction. Numerous mutations have already been transmitted to the mouse germline including alpha7 null, alpha7 L247T, alpha5 null, alpha3 null, beta4 null, and beta2 null. This core will provide the initial characterization of the phenotype for each mutation including survival analysis and basic clinical observations, Mice will be provided to the various collaborators for baseline neuropathological, behavior, and electrophysiological studies. When supplying mice to the various projects for in depth studies, the Core will provide genetic expertise and participate in experimental designs to determine breeding strategies, background genotype for mutations, types of mutations to be produced, feasibility of using blinded observations, numbers of animals needed for experimentation, and related aspects of each project. In addition to the mutations already available, the Core will produce the following mutations: alpha4 null, alpha3 conditional null, alpha7 conditional null, beta4 conditional null, and a null to L247T conditional mutation. The alpha4 null mutation will be prepared by deletion of essential exons. Conditional null mutations will be achieved by standard methods for preparation of flox premutations (exons flanked by loxP sites), and these will be bred to mice carrying inducible Cre transgenes or tissue-specific Cre transgenes to obtain inducible conditional mutations and tissue- specific conditional mutations as detailed in the proposal. Various double and triple mutations have been and will be produce using breeding of unlinked single mutations or introduction of multiple mutations within a single gene cluster in ES cells. In addition to providing the mutant mice to the projects within this proposal, mutant mice will be offered to the Jackson Laboratories for distribution within the research community shortly after publication. The mutant mice produced by this Mouse Genetics Core should prove invaluable for extensive studies involving the function of neuronal nAChRs an their role in nicotine addiction.